1. Field of the Invention
This invention relates to a flow control device for limiting water flow to sprinkler heads in lawn sprinkler systems, and for preventing water waste from broken sprinkler heads.
2. Description of Related Art
In typical lawn sprinkler systems, manifolds of water supply pipes extend beneath the surface to be watered. Sprinkler heads are spaced at intervals around a matrix of buried supply pipes, and are attached to the underground pipes through risers which threadedly engage subterranean fittings and extend vertically to, or above, the surface of the ground. A plurality of heads are usually served through a single valve.
Sprinkler heads may be of the fixed or pop-up variety. Pop-up sprinkler heads allow the sprinkler head to mount relatively close to the surface of the ground, elevating only when activated by water pressure resulting from actuating a valve to the system, either manually or electrically. When the water pressure is shut off, a pop-up sprinkler head will return to its resting position.
A very common problem with lawn sprinkler systems is damage to the sprinkler heads caused accidentally or by vandalism, or loss of heads to theft. Sprinkler heads are easily knocked off by pedestrian traffic, children playing on the lawn, lawn maintenance personnel and equipment, and the like. Typically, a single sprinkler valve will service a manifold having multiple sprinkler heads, frequently up to six or eight per line. When one sprinkler head is knocked off, water gushes from the broken line, often creating a geyser a number of feet in the air. Depending on the water pressure and the size of the line, water loss through a broken sprinkler head can be anywhere from 10-45 gallons per minute. Thus, even in a short sprinkler cycle, hundreds of gallons of water will be wasted through a broken sprinkler pipe. In addition, flow is diminished through the other sprinkler heads on the line to the point where, if the broken head is not promptly repaired, landscaping will die around the other sprinkler heads on the line. In residential settings, since lawn sprinklers may be activated by a clock for only a few minutes at a time, a broken head may not be noticed for many days, resulting in flooding and erosion in the small area where the system is broken, dying of grass in the area of adjacent sprinkler heads, and a very substantial waste of water.
The problem resulting from damage to lawn sprinkler lines has been very well known for many years, and many attempts have been made to minimize the consequential damage caused by broken sprinkler systems. For example, Yianilos, U.S. Pat. No. 5,372,306, shows a sprinkler head mechanism having an upstream valve which closes automatically when the sprinkler head is removed. Similar devices are disclosed in Brown, et al., U.S. Pat. No. 6,260,575, U.S. Pat. No. 6,263,911, and U.S. Pat. No. 6,263,912. A flow control valve in the line shuts when the water flow exceeds a certain predetermined amount, precluding water loss from a broken sprinkler head.
Other check valves located upstream of the sprinkler head are shown in Scaramucci, U.S. Pat. No. 4,852,603 and Yianilos, U.S. Pat. No. 5,372,306. Scott, U.S. Pat. No. 5,927,607 shows a commercial pop-up sprinkler head having an inlet flow check valve assembly with a velocity control disc that helps to meter incoming air and/or water during the initial opening of the check valve assembly, resulting in a slower pop-up stroke of the riser and a lower impact at the end of the stroke. All of the known prior art involves somewhat complex check valve assemblies which are relatively expensive and which are difficult to retrofit on existing lawn sprinkler systems.